1. Field of the Invention
The present invention pertains generally to sprinkler systems and methods for extinguishing fires, and more particularly to an electrical detector actuated fire sprinkler system for shipboard magazines which provides high reliability, low maintenance fire protection through use of solid state electronic heat detection and by providing real-time graphic display data regarding magazine thermal conditions and fire fighting efforts.
2. Description of the Prior Art
Shipboard fires involving ordnance have long posed one of the most important threats to overall ship operation, including hull, mechanical, electrical and combat systems, as well as crew safety. Onboard ordnance fires have historically cost lives, lost mission days, and substantial expense due to repair and replacement of destroyed or damaged equipment, systems and compartments.
Magazine fire threats generally include indirect heat-up of munitions in the magazine resulting from fire in adjacent compartments, fires within the magazine which do not involve ordnance, and magazine fires involving ordnance. Once an ordnance item is heated or ignited, it may detonate, explode or burn, depending upon the explosive or propellant formulation and confinement of the ordnance. These reactions can then propagate to adjacent ordnance. Fragment or shaped-charge jet impact of solid-propellant rocket motors can initiate a propellant fire in a magazine. Once solid rocket motor propellant is ignited, it generally cannot be extinguished and will burn to completion. This type of burning facilitates propagation of a burning reaction to other solid propellant rocket motors or other items stored in the magazine in a process known as "fratricidal burning."
Conventional shipboard fire protection control systems for magazines have generally been designed to operate independently of electric power supply, following the philosophy that critical systems should be able to operate independently from power supplies which may undergo interruption during combat or other situations. Thus, shipboard fire sprinklers typically utilize hydraulic or pneumatic systems having large numbers of hydraulic and pneumatic components and valves and complex arrangements of pressure tubing. In such systems, heat sensors, upon detecting heat, transmit air or fluid pressure via pressure tubing to pneumatically or hydraulically activated valves which release water into the sprinkler system.
Currently used hydraulically and pneumatically activated fire sprinkler systems, however, have too numerous drawbacks. Particularly, hydraulic and pneumatic systems suffer from high incidences of false alarms which result in water damage to stored ordnance. Such false alarms are due in part to the pneumatically released valves used with such systems, which are generally very sensitive to the manner in which they are set and reset. These valves are often reset incorrectly by crew members, and the incorrectly set valves are easily "tripped" and result in water flow through the magazine sprinkler system. Additionally, the hydraulic and pneumatic components of such systems are prone to leakage and require frequent maintenance. Further, hydraulic and pneumatic control systems require large and complex arrangements of high-pressure lines or tubing which are inherently heavy and add to the overall weight of the ship. Still further, pneumatically released valves used with such systems are relatively complex and expensive and add to the overall cost of fire sprinkler systems. Finally, electrical power backup systems have become available which eliminate the need for hydraulically and pneumatically activated magazine sprinkler systems.
Another deficiency in currently used shipboard magazine fire sprinkler systems is that such systems provide no feedback to shipboard personnel regarding magazine temperature conditions and the effectiveness of fire fighting efforts. The only feedback provided by presently used magazine fire sprinkler systems is usually a simple alarm bell and or alarm light which alerts personnel to the presence of a potential fire situation. Thus, in order to determine if a fire is in progress or if fire fighting efforts are effective, a crew member is often sent to physically "feel" or touch the door to the magazine and or bulkheads adjacent to the magazine. Such methods of evaluating magazine fire conditions are inherently dangerous and unreliable.
Accordingly, there is a need for an electrical detector actuated magazine sprinkler system which uses solid state electronic fire detection and does not rely on hydraulic or pneumatic activation, which is not prone to false alarms or leakage, which does not cause inadvertent magazine flooding and ordnance damage, which is simple and lightweight, which utilizes inexpensive components, which requires low maintenance, and which provides real time feedback regarding magazine temperature conditions and fire fighting efforts. The present invention satisfies these needs, as well as others, and generally overcomes the deficiencies found in the background art.